Sprocket or gear



Oct. 1 4 1947. me. WOLFE I 2,429,008

SPROCKE'I OR 'GEAR Filed Dec. 1, 1945 3 I N VEN TOR.

Puss! G/Wf,

i atented Oct. 14, 1947 UNITED STATES OFFICE SPROCKET OR GEARApplication December 1, 1945, Serial No. 632,268,

Claims.

My invention relates to toothed, annular, power-transmitting elementssuch as sprockets and gears, and more particularly to a sprocket or geardivided diametrically into two sections.

In man instances gears or sprockets are mounted on rotatable elementsfrom which they cannot readily be removed by axial movement. In suchcases, the gear or sprocket is frequently sawed into two halves adaptedto be bolted or otherwise secured in complementary relation against theface of a flange on the rotatable element with which they are to beassociated. Because of the sawing operation by which the gear orsprocket is divided, there is usually some possibility of relativeangular movement of the two halves of the sprocket or gear when they arepositioned against the face of the flange to which they are to besecured. Proper meshing of the teeth of the sprocket or gear with anassociated chain or other gear requires that the two halves be properlyspaced with respect to each other about the axis of rotation.

It is an object of my invention to facilitate the installation of adivided gear or sprocket and to provide means which will positivelylocate the two halves of such a divided gear or sprocket in properrelation. Another object of my invention is to provide a simple andeffective means by which the two halves of a divided gear or sprocketmay be interconnected so that they can be handled as a unit.

In carrying out my invention, the gear or sprocket, formed with acentral opening and a peripheral series of teeth, is provided with twoholes the axes of which preferably are parallel to the axis of the gearor sprocket and disposed generally diametrically opposite each other.The gear or sprocket is then divided into two sections by slots or kerfsextending from each of such holes to the outer periphery and to thecentral opening of the gear or sprocket. In the preferred embodiment,the two inner slots, which connect the holes with the central opening,communicate with the holes at points located on one side of the planecontaining the axes of the two holes, while the two outer slotscommunicate with the holes on the other side of such plane. When it isdesired to assemble the two halves of the gear or sprocket, such twohalves are placed in complementary relation, and pins corresponding insize to the two holes are inserted therein.

In the accompanying drawing, which illustrates a preferred embodiment ofthe invention, Fig. 1 is an end elevation and Fig. 2 is a side elevationin partial section showing a sprocket and its mounting; and Fig. 3 is afragmental diagrammatic view illustrating the principles involved.

In the device illustrated in the drawing a shaft I0 carries a hub IIprovided with an annular flange I2 against the face of which a dividedsprocket is to be secured, as by means of bolts I3. The sprocket, whichin finished form comprises two sections Ida and Mb, is initially made asa continuous annulus provided with a peripheral series of teeth I5 andwith a central bore I6 adapted to fit the body of the hub II. After thesprocket has been formed as just described, it is provided with twogenerally diametrically opposite holes Ila and Nb conveniently locatedapproximately midway between the surface of the bore I6 and the roots ofthe teeth I5. The holes Ila and III) are connected with the central boreIt by saw kerfs or slots I 8a and with the periphery of the sprocket bykerfs or slots I8b. Such slots, in conjunction with the holesthemselves, divide the unitary sprocket into the two sections Ida andNb. In order that both sprocket-sections Ma and I4?) may be applied tothe hub II by movement in a plane normal to the axis of the shaft I0, itis desirable that the two slots I8a communicate with the central bore I6at diametrically opposite points. It is also desirable that each outerslot I8b reach the periphery of the sprocket at the bottom of a spacebetween two adjacent teeth, thus avoiding any weakening of a tooth andany interruption of the surface over which driving efiort is transmittedbetween the sprocket and an associated chain.

When the sprocket is to be put in place, the two halves are brought intoassociation with the hub II by independent movement, and pins 20a and 2%corresponding in size to the holes Na and III) are placed therein asindicated in the drawing. If the slots I8a and I8b are properlyarranged, as more particularly set forth below, insertion of the twopins 2|] will not only locate the two sections of the sprocket in theproper angular relation, but will also hold them positively in thatrelation so that the two sections may be handled as a unit. With thepins in place, the assembled sprocket is brought against the flange I2and secured in place by the bolts I3.

The conditions which must obtain in order that circular pins 20 may holdthe two sprocket sections in fixed relative position will be apparentfrom the somewhat diagrammatic illustration constituting Fig. 3. In thatfigure, the section I4!) is indicated as engaging the pins 20a and 20bover surfaces 25a and 25b respectively. The lines 26 and 21 areintersecting tangents to the surface 25a at its ends. Lines 28 and 29are drawn from the center of pin 20a perpendicular respectively to thetangents 26 and 21. Lines 30 and 3| extend from the center of pin 2%parallel respectively to the lines 28 and 29. It will be evident thatthe sprocket-section Mb can move away from pin 20a only in a directionlying between the directions of the tangents 26 and 21 and thattoprevent such movement some portion of the surface 2% must lie betweenthe lines 313 and 3|. In other words, the surface 25b must contain aportion which faces in a direction directly opposite to that in whichsome portion of the surface 25a. faces.

What is true of the surfaces 25a and 25b is.

equally true of the two pin-engaging surfaces of the sprocket-sectionMa; and in consequence, the two pin-engaging surfaces of eachsprocket-section must respectively possess portions which face inopposite directions. In addition, each pin-engaging surface of eachsprocket-section should include portions lying on opposite sides of theplane containing the axes of the two pins ZUaand 20b in order to make itimpossible for either section to swing about the axis of one or theother of the pins.

The conditions just set forth are most fully met when the two slotsassociated with each hole communicate therewith at the ends of theholediameter normal to the plane of the hole-axes, the two inner slotsl8a communicating with the holes on one side of such plane and the'outerslots 18b communicating with the holes on the other side of such plane.However, if the pins 20 fit the holes with reasonable tightness, aconsiderable departure from the ideal slot arrangement may exist withoutresulting in any adverse effect.

While I have shown the pins Zila and 291) as extending only through thesprocket and as having no function in holding the sprocket against theflange l2, such characteristics of the pins are obviously not materialto their function of locating the two sprocket-halves relative to eachother; and it is therefore to be understood that the term pins includesbolts or screws which, although they fit the holes Ha and Ill) to locatethe two sprocket-halves in fixed relative position, also perform otherfunctions such as that of holding the sprocket against the flange l2, Itwill be obvious notonly that the pins 280. and :Zfibserve to facilitatemounting of the sprocket by securing the two halves'together but thatthey also prevent any relative angular movementpf the twosprocket-halves should the securing bolts 13 .become loose in service.

I claim as my invention:

1. A power-transmitting element, comprising a circular disk having acentral opening and a peripheral series of teeth, said disk beingprovided with holes on opposite sides of said central opening, with aninner slot extending from each hole to the central opening, and with anouter slot extending from each hole to the periphery of the disk, saidholes and slots extending axially through said disk to divide it intotwo sections, and a, pin disposed in each hole, the slots associatedwith each hole communicating therewith at spaced points whereby thehole-wall is divided into two pin-engaging surfaces located on therespective disk-sections, the two pin-engaging surfaces of each sectionrespectively including portions which face in opposite directions.

2. A power-transmitting element, comprising a circular disk having acentral opening and a peripheral series of teeth, said disk beingprovided with holes on opposite sides of said central opening, with aninner slot extending from each hole to the central opening, and with anouter slot ex,- tending from each hole to the periphery of the disk,said holes and slots extending axially through said disk to divide itinto two sections, and a pin disposed in each hole, the slots associatedwith each hole communicating therewith at substantially diametricallyopposite points whereby the hole-wall is divided into two pinengag-ingsurfaces located on the respective disksections, the two pin-engagingsurfaces of each section respectively including portions which face inopposite directions.

3. The invention set forth in claim 1 with the addition that said innerslots communicate with said central opening at substantiallydiametrically opposite points.

4. The invention set forth in claim 1 with the addition that each ofsaid outer slots meets the periphery at a point between adjacent ones ofsaidteeth.

5. A power-transmitting element, eomprisinga circular disk having acentralopening and a peripheralser-ies of teeth, saiddisk beingprovided. with holeson opposite sides of said central open,- ing, withan inner slot extending from each hole to the-central opening, and withanouterslotextending from each'hole to the periphery of the disk, saidholes and slots extending axially through said disk to divideit into twosections, and a pin disposed in each hole; said holescommunicating withsaid'inner slots on one side of, and'with said outer slots on the othersideof the p n ontaini the xe of bothz o s- RUSSE WQLi IE.

